Question

a recent study of 25 students showed they spent average of $18.53 on gas per week, the sample standard deviation of the sample was $3.00, construct a 95% confidence interval for the mean amount spent on gas per week

Answer #1

Here we need to use t-test as n < 30 and population standard deviation is not given.

For df = 24 and 95% confidence interval t value is 2.06

Confidence interval:

Statcrunch output:

So, the confidence interval is **(17.29,
19.77).**

Question 4 1 pts A recent study of 25 students showed that they
spent an average of $18.56 on gasoline with a standard deviation of
$2.80. Find a 99% confidence interval for the population mean using
interval notation.
18.56 ± 0.958
(16.994, 20.126)
18.56 ± 1.156
(17.602, 19.518)
18.56 ± 1.024

a study of 25 drivers showed that they drive an average of 300
miles a week with a standard deviation of 20 miles. Identify the
distribution used (t or z) and find and interpret a 95% confident
interval for the average number of miles all drivers drive in 1
week. 2. A study of 50 students at a college showed that the
average age was 20.2 with a standard deviation of 1.8. Identify the
distribution used (t or z) and...

The mean number of hours of study time per week for a sample of
554 students is 22. If the margin of error for the population mean
with a 95% confidence interval is 2.1, construct a 95% confidence
interval for the mean number of hours of study time per week for
all students.

A study of 25 recent undergraduates found that the average
amount owed in student loans was $55,051, with a standard deviation
of $7,568.
Construct a 90% confidence interval for the population
mean.
Is it reasonable to conclude that the students actually owe
$60,000 on average in student loans? Why or why not?

A random sample of 90 UT business students revealed that on
average they spent 8 hours per week on Facebook. The population
standard deviation is assumed to be 2 hours per week.
If we want to develop a 95% confidence interval for the average
time spent per week on Facebook by all UT business students, the
margin of error of this interval is
The 95% confidence interval for the average time spent per week
on Facebook by all UT business...

In order to determine how many hours per week freshmen college
students watch television, a random sample of 25 students was
selected. It was determined that the students in the sample spent
an average of 19.5 hours with a sample standard deviation of 3.9
hours watching TV per week. Please answer the following questions:
(a) Provide a 95% confidence interval estimate for the average
number of hours that all college freshmen spend watching TV per
week. (b) Assume that a...

You want to study the average time per day spent on using mobile
phones by students at an university. Your goal is to provide a 95%
confidence interval estimate of the mean time per day. Previous
studies suggest that the population standard deviation is about 4
hours per day. What sample size (at a minimum) should be used to
ensure the the sample mean is within
(a) 1 hour of true population mean?
(b) 0.5 hour of true population mean?

A recent study reported that for a sample of 50 kitchens with
gas cooking appliances monitored during a one-week period, the
sample mean CO2 level (ppm) was 726.15, and the sample standard
deviation was 133.56.
a) Calculate and interpret 90%, 95% and 99% confidence interval
for true average CO2 level in the population of all homes from
which the sample was selected.
b) Approximating population standard deviation with sample
standard deviation, what sample size would be necessary to obtain
an...

A professor wants to estimate how many hours per week students
study. A simple random sample of 78 students had a mean of 15.0
hours of studying per week. Construct and interpret a 90%
confidence interval for the mean number of hours a student studies
per week. Assume the population standard deviation is known to be
2.3 hours per week

A questionnaire about study habits was given to a random sample
of students taking a large introductory stats class. The sample of
35 students reported that they spent an average of 115 minutes per
week studying stats. Assume that the standard deviation is 40
minutes.
A) Give a 95% confidence interval for the mean time spent
studying stats by students in this class.
B) Is it true that 95% of the students in the class have weekly
studying times that...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 9 minutes ago

asked 9 minutes ago

asked 14 minutes ago

asked 16 minutes ago

asked 19 minutes ago

asked 19 minutes ago

asked 23 minutes ago

asked 28 minutes ago

asked 28 minutes ago

asked 38 minutes ago

asked 58 minutes ago

asked 1 hour ago